Keep old Wastegate?
04-26-2003, 02:25 AM
#1
Three Wheelin'
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Keep old Wastegate?
I am wondering if the OEM factory wastegate after 100k miles can be reused after shimming? Wouldn't the wastegate's valve and seats be somewhat pitted allowing leakage even when fully seated? I've never taken out a high mileage wastegate out for closeup inspection so I am interested what is your experience with this issue? <img border="0" alt="[oops]" title="" src="graemlins/oops.gif" />
04-26-2003, 03:52 AM
#2
Race Car
Peter
The factory wastegate is OK for stock power ratings. More than that and exhaust pressures and weakened springs tend to open the wastegate too early. By design the exhaust flow pushes the valve off the seat prematurely.
I've noticed on several wastegates during disassembly that the seat will be cracked which if left unattended can cause the seat to break into multiple pieces and keep the valve from seating altogether, limiting boost by allowing exhaust to bypass the turbo.
If you're going to disassemble one, remove the nipple to reveal an allen fitting inside.
Hold backup there when you turn the valve (with allen) anti-clockwise to avoid damaging the rubber diaphram while removing it.
A seal as precise as a cylinder head valve isn't as critical here for reasons listed above, but you can lap it just the same and sealing surfaces will be restored as new.
Also I find the method of shimming with washers to be insufficient because the diphram will only be supported by a small surface area between itself and the body of the wastegate allowing the metal of the diapram base to flex, thus negating some of the benefit of shimming.
Make a pattern and cut out an aluminium shim that will support the entire base dimensions.
You'll find that the gradual opening will be affected some and the boost 'hit' will be more abrupt, at least in my experience.
Go for the Tial 35 or 38mm from SFR if you want a quality replacement with adapters. If you reverse the torque tube clamp bracket that attaches to the WG dumptube pipe you can retain it for support.
Awesome upgrade......
The factory wastegate is OK for stock power ratings. More than that and exhaust pressures and weakened springs tend to open the wastegate too early. By design the exhaust flow pushes the valve off the seat prematurely.
I've noticed on several wastegates during disassembly that the seat will be cracked which if left unattended can cause the seat to break into multiple pieces and keep the valve from seating altogether, limiting boost by allowing exhaust to bypass the turbo.
If you're going to disassemble one, remove the nipple to reveal an allen fitting inside.
Hold backup there when you turn the valve (with allen) anti-clockwise to avoid damaging the rubber diaphram while removing it.
A seal as precise as a cylinder head valve isn't as critical here for reasons listed above, but you can lap it just the same and sealing surfaces will be restored as new.
Also I find the method of shimming with washers to be insufficient because the diphram will only be supported by a small surface area between itself and the body of the wastegate allowing the metal of the diapram base to flex, thus negating some of the benefit of shimming.
Make a pattern and cut out an aluminium shim that will support the entire base dimensions.
You'll find that the gradual opening will be affected some and the boost 'hit' will be more abrupt, at least in my experience.
Go for the Tial 35 or 38mm from SFR if you want a quality replacement with adapters. If you reverse the torque tube clamp bracket that attaches to the WG dumptube pipe you can retain it for support.
Awesome upgrade......
04-26-2003, 10:21 AM
#3
Drifting
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It depends on the condition of your wastegate.
My stock shimmed 150,000 mile wastegate performed wonderfully. Boost built quickly and held like a rock (up to 20-22 psi). I have no appreciable performance improvement after going to a 45mm dual port wastegate. In both instances I had (have) manual boost control. I'm sure there's more to be had now with the dual port if I go to an EBC.
My stock shimmed 150,000 mile wastegate performed wonderfully. Boost built quickly and held like a rock (up to 20-22 psi). I have no appreciable performance improvement after going to a 45mm dual port wastegate. In both instances I had (have) manual boost control. I'm sure there's more to be had now with the dual port if I go to an EBC.
04-26-2003, 01:12 PM
#4
Three Wheelin'
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To 951and944S & Russ Murphy,
Thanks for your valuable and interesting feedback <img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />
Thanks for your valuable and interesting feedback <img border="0" alt="[cheers]" title="" src="graemlins/beerchug.gif" />
04-26-2003, 05:01 PM
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</font><blockquote><font size="1" face="Verdana,Tahoma,Helvetica">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Helvetica">Originally posted by Russ Murphy:
<strong>It depends on the condition of your wastegate.
My stock shimmed 150,000 mile wastegate performed wonderfully. Boost built quickly and held like a rock (up to 20-22 psi). I have no appreciable performance improvement after going to a 45mm dual port wastegate. In both instances I had (have) manual boost control. I'm sure there's more to be had now with the dual port if I go to an EBC.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">same here! some works good. other do not works good. It depends on how good is the spring in your wastegate.
Konstantin
<strong>It depends on the condition of your wastegate.
My stock shimmed 150,000 mile wastegate performed wonderfully. Boost built quickly and held like a rock (up to 20-22 psi). I have no appreciable performance improvement after going to a 45mm dual port wastegate. In both instances I had (have) manual boost control. I'm sure there's more to be had now with the dual port if I go to an EBC.</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Helvetica">same here! some works good. other do not works good. It depends on how good is the spring in your wastegate.
Konstantin